Looks awesome so far! :T I like the idea of the little 1/8" roundover to smooth that last edge a bit. Are you going to roundover the other four edges of the baffle to match inside? From what I understand besides looking really cool it reduces standing waves.
Single SI HT 18 build
Hey. Thought I'd make a build thread of my new sub beings that I like reading them and maybe others do too. This is my second DIY speaker project, but I'm far from being much good at it. Im still learning woodworking and about as far from an engineer as you can get. I've been reading threads here and elsewhere for quite awhile now and have learned a lot. This is a great forum.
So I picked up an SI HT 18 on preorder, seemed like a good deal. I've modeled all of the 15's and 18's in my price range and decided on a single 18 in a sealed box. I know I lose some SPL down low compared to ported, but the simplicity of the build as well as knowing how a sealed box in this room sounds steered me in this direction. Im replacing an old Velodyne F-1200 which did surprisingly well. I think I'm fortunate to have some nice room gain here.
I went with a box with outside dimensions of 34"h X 24"w X 21.75"d. Using .75" thick mdf sandwiched to .75" plywood for sides and back. Double .75" mdf for top and bottom. Baffle is 2 layers of .75" ply plus a .75" layer of mdf for the front. All bracing is double .75" mdf. After calculating the bracing volume I end up with about 5.75 cubic feet inside. I know its probably overkill and will be heavy, but my design philosophy is if its worth building, its worth overbuilding.:T
Now for some pics.
Beer and power tools.
![Tool Machine Toolroom Wood shaper Table saw]()
Gluing the baffle
![Workbench Wood Table woodworking Tool accessory]()
ply from home depot. Had to squeeze a bunch of glue in and clamp up.
![Wood Plywood Table Furniture Hardwood]()
![Workbench Wood Machine Table Tool]()
Gluing in bracing
![Workbench Wood Table Plywood Furniture]()
![White Architecture Black-and-white Line Monochrome]()
![Machine Machine tool Photography]()
![Machine]()
![Metalworking hand tool]()
![Black-and-white Monochrome Machine Monochrome photography Photography]()
![White Black Black-and-white Monochrome photography Monochrome]()
More pics to come.
So I picked up an SI HT 18 on preorder, seemed like a good deal. I've modeled all of the 15's and 18's in my price range and decided on a single 18 in a sealed box. I know I lose some SPL down low compared to ported, but the simplicity of the build as well as knowing how a sealed box in this room sounds steered me in this direction. Im replacing an old Velodyne F-1200 which did surprisingly well. I think I'm fortunate to have some nice room gain here.
I went with a box with outside dimensions of 34"h X 24"w X 21.75"d. Using .75" thick mdf sandwiched to .75" plywood for sides and back. Double .75" mdf for top and bottom. Baffle is 2 layers of .75" ply plus a .75" layer of mdf for the front. All bracing is double .75" mdf. After calculating the bracing volume I end up with about 5.75 cubic feet inside. I know its probably overkill and will be heavy, but my design philosophy is if its worth building, its worth overbuilding.:T
Now for some pics.
Beer and power tools.
Gluing the baffle
ply from home depot. Had to squeeze a bunch of glue in and clamp up.
Gluing in bracing
More pics to come.
21 - 40 of 73 Posts
Long work day so I didnt get anything done on the box, maybe tomorrow. yes I do plan a roundover on the outside, probably just on the sides and leave the top and bottom just sanded over a bit. I picked up an inexpensive 1" radius roundover so Ill give that a try.
![Axe Dane axe Hatchet Antique tool Broadaxe]()
Hold on to that router with those helicopters. 
I have a 1" and 1 1/4" I use. They will run away on you if you dont watch.
I have a 1" and 1 1/4" I use. They will run away on you if you dont watch.Good advice on the big roundover bit, I thought I'd start with a 1/2" bit then ease into the 1". I only have 4 edges to do so I'll take it slow.
Worked on mounting hardware for the woofer today. After a long work day so I was kind of beat, but still I think things turned out ok.
Started out using a cheap 1/8" roundover bit on the outside woofer cutout. Exactly what I wanted.
![Architecture Material property Wood Beige Circle]()
I had an issue with just loose fitting the mounting screws through the woofer holes. First off I'm using 1/4" bolts and t-nuts. I thought maybe the big thick rubber gasket-tire like thing fitted on the outside of the metal basket itself is only meant for 3/16" bolts. So I looked at it from the back side, pulling the thick rubber gasket away so I could see the hole itself. It seemed plenty big. I realized that I'm not going to get a good fit with this big rubber gasket on, so I just took it off. Luckily, I guess, its not glued on. Then I seen I had another problem. The surround. Yeah its really tall and high and excursion capable. It's also thick, at least a 1/16". My particular surround was also glued on like this:
![Tire Automotive exterior Rim Automotive tire Bumper]()
Every hole. If its not clear from the pic; the surround holes aren't glued in place with the basket holes. Sometimes an 1/8" is important. I tried one hole, just pushing through the surround; yeah this happens:
![Electronics Furniture Technology Electronic device Audio equipment]()
Well that's just ugly. I then took a new exacto knife and very carefully cut out every hole, which is not easy, like I said this is some thick rubber. An hour later I had shaved away enough to see the actual basket holes. Hell yeah! Now I know where to drill.
Make shift 90 degree jig.
![Wood Plywood Table]()
Thanks to dougc and his killer build for his excellent visual tutorial on how to install t-nuts.
This is after all t-nuts in glued and dried.
![Wood Plywood Window Metal]()
1/2" Chamfer action. I already had this bit, so didnt want to buy a bigger one. I think it will work well enough though. It might be a bit dull though. Get it, a "bit" dull. Humor, I love it!
![Wood]()
Yep, its dull, plus I was going slow to see things.
![Wood Table Rim Architecture Wheel]()
Thats it for today.
Worked on mounting hardware for the woofer today. After a long work day so I was kind of beat, but still I think things turned out ok.
Started out using a cheap 1/8" roundover bit on the outside woofer cutout. Exactly what I wanted.
I had an issue with just loose fitting the mounting screws through the woofer holes. First off I'm using 1/4" bolts and t-nuts. I thought maybe the big thick rubber gasket-tire like thing fitted on the outside of the metal basket itself is only meant for 3/16" bolts. So I looked at it from the back side, pulling the thick rubber gasket away so I could see the hole itself. It seemed plenty big. I realized that I'm not going to get a good fit with this big rubber gasket on, so I just took it off. Luckily, I guess, its not glued on. Then I seen I had another problem. The surround. Yeah its really tall and high and excursion capable. It's also thick, at least a 1/16". My particular surround was also glued on like this:
Every hole. If its not clear from the pic; the surround holes aren't glued in place with the basket holes. Sometimes an 1/8" is important. I tried one hole, just pushing through the surround; yeah this happens:
Well that's just ugly. I then took a new exacto knife and very carefully cut out every hole, which is not easy, like I said this is some thick rubber. An hour later I had shaved away enough to see the actual basket holes. Hell yeah! Now I know where to drill.
Make shift 90 degree jig.
Thanks to dougc and his killer build for his excellent visual tutorial on how to install t-nuts.
This is after all t-nuts in glued and dried.
1/2" Chamfer action. I already had this bit, so didnt want to buy a bigger one. I think it will work well enough though. It might be a bit dull though. Get it, a "bit" dull. Humor, I love it!
Yep, its dull, plus I was going slow to see things.
Thats it for today.
No problem, it took me a while to wrap my head around the math when I first toyed with the idea. I use this method to route the recess for drivers, instead of routing the cutout then rabbeting for the recess. Anyway, back to our topic.
I never thought of using a larger bit for routing out the hole. Beings that I would have had to buy one I would have just drilled an extra hole in my jig anyway. Im cheap that way.
As for the non matching holes on the woofer, it wasnt so much the curling of the surround when tightening the bolts down. I figured out that a small washer would help with that, but it was just the difficulty that it created in seeing the actual holes and pushing a bolt through. A little trimming and all is good to go now, so no harm no foul. Its nice to see someone from the company reading the forums and acknowledging an issue with their product. I have to say other than that small issue the driver seems very well put together and very impressive, especially considering the price.
Glued up the baffle today. First the double layer plywood inner baffle.
![]()
Then the outside mdf piece.
![Scale model Naval architecture]()
I really need to get some more bar clamps, I hate relying on all those screws. Oh well maybe next time.
I weighed the baffle pieces before I glued them up. Taking the 135 lbs I had before the baffle, then adding the 29 lbs for the baffle then the 52 lbs for the driver, Im looking at 216 lbs. Uhg.
Im really getting amped to get this thing rumbling. I picked up a Beringer EP 4000 on Amazon Prime for $275 shipped awhile back. Its more power than I need but for that price I figured I could only use one channel for now then possibly run another 18 later on with the other channel. I'll probably pick up a mini DSP too, though Im going to try it without just so I know the difference.
Tomorrow night I'll start on the finish; filling screw holes with wood filler and sanding. I bought some bondo and meant to try it out but man, the smell. My garage is also my studio, so I work in there during the day so I try to limit noxious vapors.
As for the non matching holes on the woofer, it wasnt so much the curling of the surround when tightening the bolts down. I figured out that a small washer would help with that, but it was just the difficulty that it created in seeing the actual holes and pushing a bolt through. A little trimming and all is good to go now, so no harm no foul. Its nice to see someone from the company reading the forums and acknowledging an issue with their product. I have to say other than that small issue the driver seems very well put together and very impressive, especially considering the price.
Glued up the baffle today. First the double layer plywood inner baffle.
Then the outside mdf piece.
I really need to get some more bar clamps, I hate relying on all those screws. Oh well maybe next time.
I weighed the baffle pieces before I glued them up. Taking the 135 lbs I had before the baffle, then adding the 29 lbs for the baffle then the 52 lbs for the driver, Im looking at 216 lbs. Uhg.
Im really getting amped to get this thing rumbling. I picked up a Beringer EP 4000 on Amazon Prime for $275 shipped awhile back. Its more power than I need but for that price I figured I could only use one channel for now then possibly run another 18 later on with the other channel. I'll probably pick up a mini DSP too, though Im going to try it without just so I know the difference.
Tomorrow night I'll start on the finish; filling screw holes with wood filler and sanding. I bought some bondo and meant to try it out but man, the smell. My garage is also my studio, so I work in there during the day so I try to limit noxious vapors.
21 - 40 of 73 Posts
